1. Field of the Invention
The present invention relates generally to drive arrangements in machines, for instances inkjet printers and the like, and, more particularly, to a drive conversion mechanism for enabling constantly meshed gears in a drive input gear train.
2. Description of the Related Art
Consumer inkjet printers typically incorporate one or more drive arrangements which allow reversing of an input while maintaining a unidirectional output. This is done to achieve system efficiency and reduce part count within the machine. Such drive arrangements have been used predominately in sheet feeding pick mechanisms of these machines, but have applications in other areas as well. In a common embodiment, the drive arrangement includes an input gear train of meshed rotary input drive gear and idler gears, usually four, mounted on a plate which idler gears are allowed to rotate or pivot fractionally about the input drive gear of the gear train. There are two idler gears on one side of the pivot, the inner one of which is meshed with the input drive gear, and one idler gear on the other side of the pivot, also meshed with the input drive gear. However, only the outer one of the two idler gears on the one side of the pivot or the one idler gear on the other side of the pivot, but not both, can be meshed at one time with a rotary output gear. The plate can be rocked about the pivot to switch meshing with the output gear from the outer one of the two idler gears on the one side of the pivot to the one idler gear on the other side of the pivot, or vice versa. This drive arrangement of the input drive gear and idler gears and switching of the meshing of the respective idler gears with the output gear thus can convert rotary motion of the input drive gear in either direction to rotary motion of the output gear in only one direction because the two idler gears that can alternately mesh with the output gear are always being driven in the same one direction when they are meshed with the output gear.
By means of a frictional restriction anywhere in the gear train, the plate will rotate within its bounds in the direction of the rotation of the input drive gear. Positioning of the output gear such that it can be engaged by either of the outer idler gear or the other idler gear mounted on the plate, and allowing for clearance such that only one of these gears may be engaged or meshed at a time, will allow the plate to rock about its pivot into the engagement or mesh with the proper one of the idler gears coinciding with the direction of rotation of the input drive gear. While this type of drive arrangement is inexpensive, effective and widely used, it has drawbacks of lost motion and time to engage the output gear with the proper one of the idler gears when reversing the direction of the input drive gear.
Thus, a need still exists for an innovation that will provide greater efficiency in a drive arrangement which allows reversing of the direction of the input while maintaining the unidirectional output.